Heretofore, halogenated heteroaryl compounds have been produced by reacting hydroxyheteroaryl compounds with thionyl halides, phosphorus oxyhalides, phosphorus trihalides or phosphorus pentahalides. These prior processes of production, however, require so severe conditions as industrially undesirable. For instance, John B. Pain III [J. Heterocyclic Chem., Vol. 24, Page 351 (1987)] and others produced halogenated heteroaryl compounds by adding a hydroxyheteroaryl compound to boiling phosphorus tribromide (bp. 173.degree. C.). However, it is difficult to control the reaction because this reaction causes a violent generation of heat. In addition, water must be added for the sake of post treatment after the reaction has been completed, which is accompanied by a generation of heat and a large quantity of hydrogen bromide. Further, the phosphorus compounds are in danger of spontaneous ignition. For these reasons, this process is undesirable as an industrial process. Thus, it has been desired to develop a process for producing halogenated heteroaryl compounds under mild conditions.
It is an object of the present invention to develop a process by which halogenated heteroaryl compounds can be produced under mild conditions.